While its good to know the underlying science, what is more important is learning how its used by brewers. For instance knowing that when gravity stops changing fermentation is done or stuck. After using it for awhile it becomes a second language and you will find yourself wanting to make an IPA that starts at 1.060 and finishes around 1.015 or a saison that starts at 1.050 and finishes at 1.007 and choosing your yeast and manipulating the fermentability of your wort accordingly.